Collection framework
The overall system diagram:
Before learning system first look iterator (Iterator) : iterator is a design pattern, it is an object that can traverse and select the object in the sequence, and the developers do not need to understand the underlying structure of the sequence. Iterator is often referred to as "lightweight" object because it created a small price.
https://www.cnblogs.com/lxqiaoyixuan/p/7156944.html
Secondly, and then look at the hash and hashCode :
hash function characteristics:
hash table (hash): https://www.jianshu.com/p/a89e9487a06c
hash和hashcode：https://blog.csdn.net/m0_37700275/article/details/82800590#commentBox
Here started learning
Collecction（set，list）:
Set:
List:
list和ArrayList：https://www.cnblogs.com/zcscnn/p/7743507.html
Basic usage comparison: https://blog.csdn.net/ftell/article/details/80826235
深入ArrayList: https://www.cnblogs.com/qingchunshiguang/p/6103731.html
Linkedlist ArrayList and contrast: https://blog.csdn.net/weixin_41657730/article/details/82462156
Map（hashmap,treemap）:
HashMap:
TreeMap: